[R-pkg-devel] Warning messages with --as-cran check

I am the author of package nleqslv.

Running R CMD check --as-cran on the package gives warning messages that I have never seen before.
The messages are similar to the following

nleqslv-package.Rd:4:1: Warning: <link> inserting "type" attribute
nleqslv-package.Rd:12:1: Warning: <script> proprietary attribute "onload"
nleqslv-package.Rd:12:1: Warning: <script> inserting "type" attribute
nleqslv-package.Rd:17:1: Warning: <table> lacks "summary" attribute

Is this serious?
What has to be done to get rid of these warning messages?

Best wishes,

Berend Hasselman